My educated guess would be the difference between hardware and software patents. There is organizations like Open Invention Network that help to support open so

My educated guess would be the difference between hardware and software patents. There is organizations like Open Invention Network that help to support open source software. Also I not sure how important this is, but AMD / Intel contribute a lot into GCC under GPLv3 which have patents grant so they can't just go after someone who using their instruction set. This of course also apply for software under Apache license 2.0.